Fluoride - is it safe to drink fluoridated water?

What is Fluoride?

Fluoride is a form of the element fluorine with an extra electron. It is nearly always found in combination with other elements such as sodium. Despite its appearance in some lists of essential vitamins and minerals, there is no firm evidence that fluoride is needed in any amount for human health. In fact it acts as a cumulative poison in the body as we only excrete about half of the fluoride we ingest.

In 1943 at a hospital in the US patients were served scrambled eggs with sodium fluoride (what is often added to toothpaste) in place of sodium chloride (salt). 163 were taken ill and 43 died. Exactly how much they had is not known, but it is well known that 250mg will provoke a toxic response and 5g is normally lethal. A tube of toothpaste can contain as much as 200mg, and for a small child this dose could be lethal. As a result of this fact, in 2007 the US introduced warnings on toothpaste tubes. The warning states that the toothpaste tube should be kept out of reach of kids of age 6 and under.

While fluoride is potentially lethal, it is found in all of us, as a result not just of fluoridated water, toothpaste, soft drinks and other man-made sources, but also because it occurs naturally in the environment. In other words a small amount is not going to harm us. The issue is just how much do we need extra fluoride. 

The problems with Fluoride.

Fluoride has been associated with a reduction in dental caries, which are the holes in the teeth that need fillings. The reduction in caries is about 15% in areas with fluoridated water. At the same time it is acknowledged that water fluoridation causes damage, called dental fluorosis, to those same teeth in 50% of the population1. Dental fluorosis involves discolouration of the teeth either with white spots or brown stains. It can also lead to pitted teeth. It looks like a fairly questionable trade off in my opinion to achieve a 15% reduction in tooth rot while 50% of the population get their teeth pitted and discoloured. These figures come from the "York study", which analysed a number of previous studies to get a general overview of what the major issues with fluoridation are.

However there appear to be more problems than are generally recognised. Excess fluoride has been associated with increases in rates of bone cancer, Downs syndrome, toxic metal absorption, particularly the neurotoxic metals aluminium and lead as well as osteoporosis and thyroid problems.

Thyroid problems.

Fluoride used to be used to treat an overactive thyroid until quite recently as it was effective at this. The doses used were in the range 2-10mg/day. This dose is pretty similar to the calculated average intake of fluoride of members of the US and UK population, 1.6-6.6mg/day. You have to wonder if ingestion of fluoride at this level is depressing thyroid function in some people.

Bone Cancer.

A study in the US in 2001 found a link between bone cancer incidence and higher levels of fluoride in the water. While the link wasn't there for most of the population boys between the ages of 6-8 were particularly at risk. It is of course a rare disease, but the risk was nevertheless established2.

Fluoride in toothpaste.

Fluoride is added to most toothpaste in the UK and the US. Sodium fluoride ( NaF) is most commonly used. However a form called stannous fluoride (SnF2), that is fluoride combined with tin, is actually more effective at reducing tooth decay and gum disease3. However this form of fluoride does cause more tooth discolouration. While the US has levels of about 1000 parts per million (ppm) of fluoride in toothpaste, here in the UK it can be up to 45% higher. This contrasts with many European countries where special toothpastes for children contain just 250-500ppm of fluoride, reflecting concern about the discolouring effects of fluoride on children's teeth in particular.

To check how much fluoride is in your toothpaste look on the ingredients list. If you are lucky it will show fluoride in parts per million (ppm), but if it shows it as a percentage of the paste then the following conversion tables should help:

Sodium Fluoride

0.32% = 1500 ppm F-
0.22% = 1000 ppm F-
0.11% = 500 ppm F-

Sodium Monofluorphospate

1.14% = 1500 ppm F-
0.76% = 1000 ppm F-
0.38% = 500 ppm F-

The truth for most people is that the fluoride they receive from toothpaste depends on their teeth brushing habits. Do you swallow any paste or do you brush with it and then spit out mouth fluids at the end of the process? Do you brush your teeth with a long wedge of flouride or just a small pea sized amount of paste? What you do will determine your fluoride load. The greater it is, the greater the possible long term health risks. It is of course possible to brush your teeth with fluoride free toothpastes or even with no toothpaste at all. This will still clear away food debris and plaque from the teeth, reducing the risk of cavaties. 

Mass medication in the water supply.

The use of fluoride in the water supply as stated above is controversial. It has the potential benefit of preventing dental caries (tooth decay) for people who eat badly. However it is a less effective way of preventing dental caries than by applying fluoride containing substances directly onto teeth, as with toothpaste.

Fluoride in the water supply also represents a form of mass medication. For someone with a good diet, with low amounts of sugars and starches, especially those in sticky forms, there will be very little tooth decay. These people's teeth are clearly worse as a result of fluoridation of water, which will lead to discolouration and pitting of teeth in as many as 50% of them. For someone who consumes a lot of sugary drinks and sweets the fluoridation will reduce damage to their teeth for a few c.15%, but will discolour the teeth of 50% of them and will actually lead to more decay of the supporting structures around the teeth such as the gingiva (gums).

It is worth noting that any benefits of fluoride occur mostly when it is used topically (i.e. applied directly to tooth surfaces). When you drink fluoridated water or swallow toothpaste, as many kids do, then the fluoride is absorbed through your intestines into your body, where it can cause a variety of ill effects depending on the dosage.

My own opinion is that the addition of fluoride to water is wrong. The medicine (fluoride) is delivered to people who contol their dosage via thirst and their drinking habits. These in no way relate to their need for the medicine. Many will have nothing to gain from the fluoride. Those for whom cavities may be prevented, could acheive what they need with toothpaste.

How much fluoride am I getting?

If you drink tap water this depends very much on where you live. For UK readers there are maps available showing the fluoride levels in your water supply4. It also depends on the type and how much and often you use toothpaste. There are other sources such as soft drinks which often contain as much fluoride as the tap water supply. Processed foods can also contain appreciable amounts of fluoride.

For those with a bit of spare cash who are concerned about fluoridated water it is possible to buy filter systems that remove most of the fluoride. One such system is available from the freshwaterfilter site5.


1) http://www.york.ac.uk/inst/crd/pdf/summary.pdf

2) http://www.webmd.com/cancer/news/20060406/does-fluoridation-up-bone-canc...

3) http://www.ncbi.nlm.nih.gov/pubmed/8593194

4) http://dwi.defra.gov.uk/consumers/advice-leaflets/fluoridemap.pdf  

5) http://www.freshwaterfilter.com/product/Fluoride_Removal_Fluoride-FW2000